My first smart phone was a myTouch3G purchased on eBay. I liked it well enough that I bought two more on Craig's List for my wife and older son. The three of us are on a family plan with data but no texting.
T-Mobile called one day to see if they could sell me anything.
I told the fellow that I would love to have a phone that was roughly the same size but with more power and more memory. He suggested the myTouch 4G and told me I could replace all three of our phones with refurbished 4Gs for $50 each - obviously with a new two-year commitment. That did not bother me, as we were satisfied with T-Mobile and did not plan to give up our smart phones.
Of the three 4Gs that we got, one was faulty and had to be replaced. Other than that, they have been trouble-free. Battery life is a bit of an issue, but not so much that we can't live with it. We have a car charger in each car and keep an AC charger plugged in and ready to use at home. I do have JuiceDefender installed on my phone because we use it as our home phone connected via BlueTooth to a PhoneLabs Dock n Talk. I have noticed that when we are traveling and I turn off BlueTooth, my battery life improves.
I have a variety of apps installed on my phone, but there are several I use more frequently.
Aldiko is an eBook reader I have used to read quite a number of books.
CamScanner uses the camera to scan documents which it crops automatically and converts to PDFs. It has allowed me to avoid the cost of replacing a scanner that died.
I have an English - Italian translator that comes in very handy.
I use MortPlayer to play an extensive collection of music.
I have a Schwab app that allows me to deposit checks into my brokerage account electronically. I can then transfer the funds to my checking accoung without ever going to the bank.
SmartAss is a shopping list app that I use weekly when we do our grocery shopping.
I have the Starbucks app installed so I can pay with my phone and not have to carry my Starbucks card.
I use vizBattery to give me an on-screen display of battery charge.
I have used my 4G for Wi-Fi calling and have also used the mobile hotspot feature when we were staying in a hotel that either did not offer a Wi-Fi connection or wanted to charge for it. We have connected both our laptops to the phone and browsed at leisure. We do use our data plan and find it very convenient when we are out and about.
To sum it up, we are very satisfied with our 4Gs and have no plans to replace them. The size is ideal for us and performance meets all our needs. Oh by the way, when we got our 4Gs I sold all three of our 3Gs on Craig's List for about what we paid for them.